Automatic firearm



C. G. SHEPPARD.

AUTOMATIC FIREARM.

APPLICATION FILED JULY 9. 1920.

Patented May 3, 1921.

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C. C. SHEPPARD.

AUTOMATIC FIREARM.

APPLICATION FILED JULY 9. I920.

- Patented May 3, 1921,

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AUTOMATIC FIREARM.

APPLICATION FILED JULY 9. 1920.

Patented May 1921.

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CREEDY C. SHEPPARD, OFWASHINGTON, DISTRICT OF COLUMBIA, ASSIGNOR TO UNITED STATES ORDINANCE COMPANY OF WASHINGTON, DISTRICT OF COLUM- BIA, A CORPORATION OF VIRGINIA.

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Specification of Letters Patent.

Patented May 3, 1921.

Application filed July 9, 1920. Serial No. 394,949.

of Washington, in the District of Columbia, have invented, certain new and useful Improvements in Automatic Firearms, of which the following'is a specification. I My invention relates to firearms and particularly those wherein a complete cycle .of operation of the breech closure mechanism is accomplished automatically by the firing of the arm.

It is my purpose to provide a firearm of this type having a breech closure mechanism which will utilize certain desirable fee-- tures described and claimed in U. S. Patent 1,291,689 granted to me January 14, 1919 and at the same time greatly simplify the construction disclosed in my aforesaid patent.

It is also my purpose to provide a breech closure mechanism for firearms adapted to embody a minimum num er ofparts characterized by simple and rugged design, which will add little if any weight to the standard army shoulder rifle now in use, and which will be effective and reliable in operation.

Furthermore, it is my purpose to provide an automatically operated breech closure mechanism of the rotatable and slidable bolt type embodying my improvements and with which the barrel, sight, stock and other parts of existing arms can be associated, thus permitting conversion of such existing arnis to automatic and semi-automatic type with a minimum of additionalparts and expense. .I will describe my invention as applied to a shoulder rifle, but it will be apparent that the same is ap li'cable to machine guns and other forms 0 guns,-and that it is suscep-- tible to changes in forms and proportions and to desirable mechanical additions with the exercise pf only ordinary mechanical skill and without departing from the scope of the invention as mt forth in the appended claims.

- In describing my invention in detail reference will be had to the accompanying drawand which will ings wherein like characters of reference denote corresponding parts .151 the several views, and In wh1ch Figure 1 is a side elevation of my im-- proved firearm; Fig. 2, a vertical section of what is shown in Fig. 1 with the breech bolt in locked position and the firing pin at the limit of its firing stroke;

1g. 3, a view similar to Fig. 1 with the firlng pin m cocked position and ready to be released for actuation by the firing sprlng to fire the arm; I

Fig. 4, a view similar to Fig. 1 with the breeeh'bolt in full open position;

Fig. 5, a plan view of the receiver. detached;

6, a section on the line 66 of Fig. 5; Fig. 7, an elevation of the bolt detached and viewed from the side when in unlocked.

position;

Fig. 8, a front view of Fig. 7;

Fig. 9, a rear view of Fig. 7

10, a side view of the firing pin;

F g. 11, a side view of the cocking piece;

F g. 12, a side view of the housing which carrles the trigger sear and magazine latch and detachably interlocks with the receiver;

. Fig. 13, a top view of the housing shown in Fig. 12; I

Fig. 14, a rear view of the guide for the combined recoil and firing spr ng;

Fig. 15, a side view 0 said guide;

Referring to the drawings my improved.

arm is shown as comprising a rear stock section A, a forward stock section B, a re- .ceiver C, and a barrel D threaded in the forward end of the receiver. The receiver C comprises a substantially tubular-body portion 20 which is provided in its upper side with a longitudinal slot 21 the rear endof which opens through the rear .end of the receiver while the forward end is enlarged laterally to one side to'provide the cartridge ejectingopening22 and a cam surface 23,

the purpose of which '1atter will presently vided with opposite lower grooves 26 and opposite upper grooves 27 for a purpose that will presently appear. Formed on the lower j tering the receiver I have provided a sliding side of the receiver are depending parallel longitudinal flanges 28 and 29 which in the assembled arm extend between the stock sections. The forward end of the receiver is secured to the stock section B by a fastening device 31, said section embracing the flanges at the point of connection and between the flanges at this point is inserted and secured a strengthening filler 'block 32.

The receiver C has its rear end closed by a cap 33 threaded thereon and housed in said receiver is a rotatable and longitudinally slidable breech bolt E having locking lugs 34 and 35"at its forward end which are adapted to-cooperate respectively with corresponding lugs 36 and 37 on the receiver to secure the bolt in closed or firing position.

The construction of the lugs 34, 35, 36 and 37 is similarv to the construction disclosed in my prior Patent 1,291,689. In other words the coacting faces of these lugs are inclined at such an angle to a plane perpendicular to the axis of the bolt that they will engage immovably during the time of "high powder pressure but will disengage under the influences of the moderate pressure obtained as and after the bullet leaves the bore. Within the bolt E is slidably engaged a hollow firing pin, 38 disposed eccentrically to the bolt and open at its rear end and receiving within. its interior a combined firing and recoil spring 39. The forward end of this spring is anchored to the firing pin at 40 while the rear end thereof is engaged over 7 a guide 41 anchored to the latter at 42. The rear end of the guide 41 has fixed thereon a disk 43 having a peripheral extension 44 of such size :as will permit it to be moved freely in the groove 21. B this construction it will be obvious tha upon slightly withdrawing the disk 43 from'the rear end of the receiver the guide 41 can be rotated to torsion the spring 39 and then reinserted into the receiver with the extension 44 in the slot 21 when the torsional action of the spring will operate to seat the extension 44 in a recess 45 in one wall of the slot 21 and thereby lock the guide against rearward movement. The forward end of the firing pin 38 terminates in a firing point 46 having an enlarged portion 46, disposed eccentrio to both the body portion of the pin and the breech bolt E; a suitable eccentric chamber 47 being provided in the breech bolt for its reception. Owing to the eccentric relationbetween the bolt E, firing pin body and the portion 46' of the firing pin point it will be apparent that the torsional action of the spring 39 operates upon the bolt through amaze the firing pin 38 and eccentric enlargement 46 of the firing pin point to keep the bolt seated in locked position or in other words in position to aline the lugs 34 and 35 with the lugs 36 and 37 respectively.

To close the slot 21 and prevent dirt enmember 48 guided in the grooves 26 and pressed forward by a spring 49 which seats at its rear end in a member 50 also slidably mounted in thegrooves 26. Forward movement of the member '48 and rearward movement of the member 50 under the influence of the spring 49 is positively limited by stops 51 and 52 respectively which depend from a sight base 53 mounted in the grooves 27 which latter are slightly converged in a forward direction to provide a snug seat for the sight base. The member 50 projects into -t a recess 54 in the cap 33 and thereby prevents removal of the cap until said member is manually forced out of said recess againstthe firing pin 38 is a cooking piece 57 which has sliding, but non-rotating engagement with the receiver and is provided with cam faces 58 which coact with similar cam faces 59 on a flange 6O at'the rear end of the firing pin to hold the firing pin point 46, away from the cartridge primer except when the bolt E is in closed or locked position.

The forward end of the extension 55 of the bolt is designed to coiiperate with the cam surface 23 on the receiver to control the movements of the bolt, the forward end of which member coacts with the cam surface 23 during unlocking rotation of said bolt to transform the energy of rotation into energy of translation while 'coaction between these parts, as the bolt moves forward or home, transforms the energy of translation into energy of rotation and thus I cking of the bolt. As has been previously Ztated the angle of the coacting faces of the bolt and receiver lugs is such that these surfaces will engage immovably during the time of high powder pressure, but will disengage and thereby impart -energy of rotation to the bolt under the influence of the relatively moderate powder pressure obtained as and after the bullet leaves the 60 ceiver, a rotatable and slidable bolt in the 7 action. By. providing the lateral extension 55 and handle 56 I position mass at a considerable distance from the axis of rotation of the bolt and thereby increase the radius of-gyration and hence the inertia efit'ect of this mass.

My arm further embodies a trigger 61,

sear 62, and magazine latch 63 all mounted between the arms 64. and 65 of a U-shaped member F. The arms ofthe member are i provided respectively with outwardly ex-.

tending cars 66 which engage respectively in slots 67 formed respectively in the deending flanges 28 and 29.0f-the receiver. hese slots are arranged at an angle to the axis of the receiver as are likewise the ears 66 so that backward pressure on the memberservesto hold said -me1nber securely in position. This ressure is exerted by a stock bolt 68 passlng'through stock section A and being threaded in the arm connecting portion of the member F. It will be ob-' "served that the operating parts carried by the receiver can be dismantled by simply removing the receiver cap and drawing them rearward, while the stock section A and the parts carried by member F can be removed by simply removing the stock bolt 68. A. safety '69 ismounted in the flan cs 28 and 29 of the receiver and the sha thereof is adapted to seat in recess 70 in the arms of the member F as the latter is interlocked with the flanges 28 and 29' in the manner heretofore referred to.

I ClfllIIlv- 1. In a firearm, the 'comblhation' of a re-' ceiver, a rotatable and slidable bolt .in the receiver, coacting lugs on the bolt and 'receiver operating .when subjected to maximum powder pressure to lock the bolt immovable and effective when subjected to the reduced pressure obtaining as the .bullet leaves the boreto impart unlocking movement to the bolt, and an extension on the bolt for imparting a relatively high moment of inertia thereto to properly eontrolits ac-" tion when energized by said powder pressure.

2. In a firearm, the combination of are-- receiver, coacting lugs on the bolt and receiver operating when subjected to maxi- .mu-mpowder pressureto lock the bolt immovable and. effect ve when subjected to the reduced pressure obtainin as the bullet leaves the bore to impart un ocking movement to the bolt and a lateral extension on the bolt producing a relatively high radius of gyration thereto and increasing the inertia effect of the mass of the bolt to propferly control its 'action when energized bysaid reducedpowder pressure. I

3. In a firearm, the combination of a reeiver a slidable and rotatable bolt, a firing pin slidable in the bolt, and a'combined re-,

coil and firing spring acting torsionally throu h the pin to rotate the bolt.

4. n afirearm, the combination of a re ceiver, a slidable and rotatable bolt, a firing pin slidably and non-rotatably mounted in the bolt, and a torsionally energized combined recoil and firing spring having its forward end anchored to the firing pin, and its rear end anchored to a part held in fixed position with respect to the receiver,

5. In a firearm, the combination of a receiver, a rotatable and slidable bolt, a firing the bolt, a' combined recoil and firing spring 7 having its forward end anchored to the firing'pm, and a spring guide detachably interlocked with the receiver and on and to which the rear end of the spring is engaged and anchored whereby said guide may be rov, pin slidably and non-rotatably mounted in tated to torsionally energize the spring and then interlocked with-the receiver.

6.. In a firearm, the combination of a receiver, a rotatable and slidable bolt, a firing pin slidably-and non-rotatably mounted in the bolt and having acircumscribing flange at its rear end, cams formed on the forward face of the flange, a. firing spring normally holding the pin at the'limit of its forward movement with respect to the bolt,

a cooking piece rotatable on the firing pin and slidably and non-rotatably" engaged with the receiver, and cams Orr-the cocking piece coacting with the cams on the. flange during unlocking rotation of the bolt to re-' tract said pin relatively to the bolt against the influence of said spring.

7 In a firearm, the combination of a ref ceiver having a longitudinal .slot therein, flanges rising fromthe receiver on each side of the slot, a sight base mounted between the flanges, depending lugs on respective ends of the sight base,-a spring seat slidable between the flanges beneath abutting) the depending lugs at the rear of the base, a dust guard for said slot slidably the sight base and mounted between the flanges and having a shoulder abutting the lug at. the forward end of the'sight base, and a spring interposed between said seat and guard normally holding the latter in extreme forward position. v

8. In a firearm, the combination of a receiver having a longitudinal slot therein, flanges rising from the receiver on each side 

